Positive photosensitive resin composition, method for forming pattern, and electronic part

ABSTRACT

Provided is a positive photosensitive resin composition which is advantageous not only in excellent sensitivity, resolution and adhesion, but also in excellent heat resistance even when the composition is cured by a low-temperature process at equal to or lower than 280° C., as well as low water absorption and capability to give a pattern with favorable configuration. The positive photosensitive resin composition contains: (a) alkaline aqueous solution-soluble polyamide having a polyoxazole precursor structure; (b) an o-quinonediazide compound; and (c) a latent acid generator which generates acid upon heating. The composition optionally further contains (d) a compound having a phenolic hydroxyl group or (e) a solvent.

TECHNICAL FIELD

The present invention relates to a heat-resistant positivephotosensitive resin composition containing a polyoxazole precursorhaving photosensitivity, a method for forming a pattern using thecomposition, and an electronic part.

BACKGROUND ART

In semiconductor devices, polyimide resins having excellent heatresistance and electrical properties as well as excellent mechanicalproperties have conventionally been used in surface protecting films andinterlayer insulating layers. In recent years, as the integration degreeof semiconductor devices is increasing and the size thereof isdecreasing, there are increasing demands on resin encapsulation packagesto be reduced in thickness or size. For meeting these demands, surfacemount modes such as LOC (lead on chip) or solder reflow are employed.Consequently, there are increasing demands on a polyimide resin to havemore suitable properties as a protective film on the uppermost surfaceof a semiconductor circuit. That is, a polyimide resin is now becomingto be required to have better mechanical properties and heat resistance.

On the other hand, also coming into use is a photosensitive polyimidewhich is a polyimide resin having sensitivity properties, and which hasa feature such that it can simplify the step of forming a pattern toshorten the cumbersome fabrication process.

Heat-resistant photoresists using the conventional photosensitivepolyimide or a precursor thereof have been well known. Examples ofnegative photosensitive resins include those obtained by introducing amethacryloyl group into a polyimide precursor through an ester linkageor an ionic bond (for example, see Patent Documents 1 to 4), a solublepolyimide having photopolymerizable olefin (for example, see PatentDocuments 5 to 10), and a self-sensitizing polyimide having abenzophenone skeleton and having an alkyl group at the ortho-position ofthe aromatic ring to which a nitrogen atom is bonded (for example, seePatent Documents 11 and 12). The uses thereof are also well known.However, the aforementioned negative photosensitive resins needs anorganic solvent, such as N-methylpyrrolidone, upon development.Therefore, there has been proposed a positive photosensitive resin whichcan be developed with an alkaline aqueous solution.

As positive photosensitive resins, there are known a positivephotosensitive resin obtained by, for example, a method in which ano-nitrobenzyl group is introduced into a polyimide precursor through anester linkage (for example, see Non-patent Document 1), a method inwhich a naphthoquinonediazide compound is mixed into solublehydroxylimide or a polyoxazole precursor (for example, see PatentDocuments 13 and 14), or a method in which naphthoquinonediazide isintroduced into soluble polyimide through an ester linkage (for example,see Non-patent Document 2). There are also known a photosensitive resincomposition obtained by mixing naphthoquinonediazide into a polyimideprecursor (for example, see Patent Document 15).

The negative photosensitive resins have a problem of poor resolution dueto light-absorption wavelength of its sensitizer. In some applications,the resins also cause a problem of low yield in the production. Further,because of the limitation in the structure of the polymer used in thepolyimide resin, the physical properties of the finally-obtained filmare also limited, which makes the resins unsuitable for multipurposeuse. Like the negative photosensitive resins, the positivephotosensitive resins have similar problems of the low sensitivity orresolution due to the problem of the light-absorption wavelength of itssensitizer, and that the structure of polymer is limited.

There have been proposed materials having introduced a phenolic hydroxylgroup instead of carboxylic acid, such as a material obtained by mixinga diazonaphthoquinone compound into a polybenzoxazole precursor (forexample, see Patent Document 16), and a material obtained by introducinga phenolic site into polyamide acid through an ester linkage (forexample, see Patent Document 17), but development properties of thesematerials are unsatisfactory. Further, they have problems of reductionin thickness of the unexposed portion, and peeling-off of the resin fromthe substrate.

For improving the development properties and the adhesion properties,there has been proposed a material containing polyamide acid having asiloxane site in the polymer skeleton (for example, see Patent Documents18 and 19), but this material has poor storage stability due to thepolyamide acid contained therein. For improving the storage stabilityand the adhesion property, a material having an amine end group cappedwith a polymerizable group has been proposed (for example, see PatentDocuments 20 to 22). However, these materials use a diazoquinonecompound containing a number of aromatic rings as an acid generator andhence have poor sensitivity. Further, because of the high content of thediazoquinone compound, the film after heat-curing results in havingconsiderably low mechanical properties, which makes it difficult topractically use the materials.

For solving the above problems bound to the diazoquinone compound,materials to which a variety of chemical amplification systems isapplied have been proposed. Examples thereof include chemicallyamplified polyimide (for example, see Patent Document 23), andchemically amplified polyimide and polybenzoxazole precursor (forexample, see Patent Documents 24 to 30). However, among these, thematerial having high sensitivity has a low molecular weight, and hencehas low film properties. On the other hand, the material havingexcellent film properties has a high molecular weight, and hence hasunsatisfactory solubility and low sensitivity. Therefore, any of thesematerials are not practical, and materials which can be put intopractical use have not yet been obtained.

REFERENCES

-   Patent Document 1: JP-S49-11541 A-   Patent Document 2: JP-S50-40922 A-   Patent Document 3: JP-S54-145794 A-   Patent Document 4: JP-S56-38038 A-   Patent Document 5: JP-S59-108031 A-   Patent Document 6: JP-S59-220730 A-   Patent Document 7: JP-S59-232122 A-   Patent Document 8: JP-S60-6729 A-   Patent Document 9: JP-S60-72925 A-   Patent Document 10: JP-S61-57620 A-   Patent Document 11: JP-S59-219330 A-   Patent Document 12: JP-S59-231533 A-   Patent Document 13: JP-S64-60630 A-   Patent Document 14: U.S. Pat. No. 4,395,482-   Patent Document 15: JP-S52-13315 A-   Patent Document 16: JP-H1-46862 B-   Patent Document 17: JP-H10-307393 A-   Patent Document 18: JP-H4-31861 A-   Patent Document 19: JP-H4-46345 A-   Patent Document 20: JP-H5-197153 A-   Patent Document 21: JP-H9-183846 A-   Patent Document 22: JP-2001-183835 A-   Patent Document 23: JP-H3-763 A-   Patent Document 24: JP-H7-219228 A-   Patent Document 25: JP-H10-186664 A-   Patent Document 26: JP-H11-202489 A-   Patent Document 27: JP-2000-56559 A-   Patent Document 28: JP-2001-194791 A-   Patent Document 29: JP-2002-526793 A-   Patent Document 30: U.S. Pat. No. 6,143,467-   Non-patent Document 1: J. Macromol. Sci. Chem., A24, 10, 1407, 1987-   Non-patent Document 2: Macromolecules, 23, 4796, 1990

DISCLOSURE OF INVENTION Problem to be Solved by the Invention

A pattern made of photosensitive polyimide or photosensitivepolybenzoxazole is usually cured at a temperature as high as about 350°C. In contrast, a recently developed MRAM (magnetoresistive RAM;non-volatile magnetoresistive memory), which is a promising memory ofthe next generation, is susceptible to such a high-temperature process,and production by a low-temperature process is desired. Therefore, as amaterial for buffer coat (surface protecting film), it is indispensableto provide with a photosensitive resin composition which can be cured ata temperature lower than the conventional curing temperature as high asabout 350° C., that is, which can be cured at a temperature as low asabout 280° C. or less, and which can form a cured film having physicalproperties comparable with the physical properties of the film cured ata high temperature.

In the present invention, by employing a specific additive together withan alkaline-developable photosensitive polybenzoxazole precursor, thereis provided a positive photosensitive resin composition which can formby a low-temperature curing process a cured film having excellent heatresistance and having physical properties comparable with those of thefilm cured at a high temperature.

In the method for forming a pattern of the present invention, theaforementioned positive photosensitive resin composition is used andtherefore, development can be performed using an alkaline aqueoussolution, and a pattern having excellent sensitivity and resolution aswell as favorable form can be obtained.

Further, a pattern having excellent heat resistance can be obtained by alow-temperature curing process at a temperature equal to or lower than280° C.

The present invention also provides an electronic part which isadvantageous not only in having a pattern having excellent configurationand properties, but also in capable of being cured by a low-temperatureprocess whereby damages on the device is prevented. Thus the electronicpart has high reliability and can be produced in high yield.

MEANS FOR SOLVING PROBLEM

The present invention relates to:

(1) A positive photosensitive resin composition comprising:

(a) alkaline aqueous solution-soluble polyamide having a polyoxazoleprecursor structure;

(b) an o-quinonediazide compound; and

(c) a latent acid generator which generates acid upon heating.(2) The positive photosensitive resin composition according to (1),wherein the component (a) is a polyamide having a repeating unitrepresented by the following general formula (I):

wherein U represents a tetravalent organic group, and V represents adivalent organic group.(3) The positive photosensitive resin composition according to (1) or(2), wherein the component (c) is a salt formed of a strong acid and abase.(4) The positive photosensitive resin composition according to any oneof (1) to (3), wherein the component (c) has a decomposition startingtemperature of 140 to 250° C.(5) The positive photosensitive resin composition according to any oneof (1) to (4), wherein the component (c) is a salt of toluenesulfonicacid.(6) The positive photosensitive resin composition according to any oneof (1) to (5), wherein the component (c) is an iodonium salt.(7) The positive photosensitive resin composition according to any oneof (1) to (6), further comprising (d) a compound having a phenolichydroxyl group.(8) The positive photosensitive resin composition according to (7),wherein the component (d) is a compound represented by the followinggeneral formula (II):

wherein X represents a single bond or a divalent organic group, each ofR³ to R⁶ independently represents a hydrogen atom or a monovalentorganic group, each of m and n is independently an integer of 1 to 3,and each of p and q is independently an integer of 0 to 4.(9) The positive photosensitive resin composition according to (8),wherein the group represented by X in the general formula (II) is agroup represented by the following general formula (III):

wherein each of two A's independently represents a hydrogen atom or aalkyl group having 1 to 10 carbon atoms, and optionally has any one ofan oxygen atom and a fluorine atom or both.(10) The positive photosensitive resin composition according to any oneof (1) to (9), wherein the content of the component (b) and the contentof the component (c) are 5 to 100 parts by weight and 0.1 to 30 parts byweight, respectively, relative to 100 parts by weight of the component(a).(11) The positive photosensitive resin composition according to any oneof (7) to (10), wherein the content of the component (b), the content ofthe component (c), and the content of the component (d) are 5 to 100parts by weight, 0.1 to 30 parts by weight, and 1 to 30 parts by weight,respectively, relative to 100 parts by weight of the component (a).(12) A method for forming a pattern comprising the steps of:

applying the positive photosensitive resin composition according to anyone of (1) to (11) onto a supporting substrate and drying thecomposition to obtain a photosensitive resin film;

exposing the photosensitive resin film to a ray of active light having apredetermined pattern; and

developing the exposed photosensitive resin film using an alkalineaqueous solution.

(13) The method according to (12), further comprising a step ofsubjecting the developed photosensitive resin film to a heatingtreatment.

(14) The method according to (13), wherein the heating treatment is atreatment of irradiating the film with a pulse of microwave whilechanging the frequency thereof.

(15) The method according to (13) or (14), wherein the heating treatmentis conducted at a temperature equal to or lower than 280° C.

(16) An electronic part comprising an electronic device having a layerof pattern obtained by the method for forming a pattern according to anyone of (12) to (15),

wherein the device comprises the layer of pattern provided therein asany one of an interlayer insulating layer and a surface protecting filmlayer or both.

(17) The electronic part according to (16) which is MRAM.

EFFECT OF THE INVENTION

With the positive photosensitive resin composition of the presentinvention, acid generated from the latent acid generator serves as acatalyst for the dehydration and cyclization reaction of the phenolichydroxyl group-containing polyamide structure of the polybenzoxazoleprecursor in the step of heating treatment for the photosensitive resinfilm that has been exposed and developed. Therefore, the cyclizationreaction or curing reaction efficiently proceeds at a lower temperature.The use of the predetermined latent acid generator does not adverselyaffect the difference of the solubility in a developer (solubilitycontrast) between the exposed portion and the unexposed portion,achieving excellent sensitivity and resolution. In the method forforming a pattern of the present invention, by using the positivephotosensitive resin composition, there can be obtained a pattern whichis advantageous not only in excellent sensitivity, resolution andadhesion, but also in excellent heat resistance and low waterabsorption, whereby a pattern having a favorable form can be obtainedeven by a low-temperature curing process.

The electronic part of the present invention is advantageous not only inexcellent configuration, adhesion and heat resistance, but also incurability in a low-temperature process, whereby the device is preventedfrom damages, and thus the electronic part has high reliability. Becauseof low damages on the device, the electronic part can be produced with ahigh yield.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view of a step in the fabrication processfor a semiconductor device having a multilayer wiring structure;

FIG. 2 is a cross-sectional view of a step in the fabrication processsubsequent to the step shown in FIG. 1;

FIG. 3 is a cross-sectional view of a step in the fabrication processsubsequent to the step shown in FIG. 2;

FIG. 4 is a cross-sectional view of a step in the fabrication processsubsequent to the step shown in FIG. 3; and

FIG. 5 is a cross-sectional view of a step in the fabrication processsubsequent to the step shown in FIG. 4.

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiments of the present invention will be explained hereinbelow.

The positive photosensitive resin composition of the present inventioncomprises, as a component (a), alkaline aqueous solution-solublepolyamide having a polyoxazole precursor structure. As to the polyamideused in the present invention, there is no particular limitation as longas it has a polyoxazole precursor structure therein and it is alkalineaqueous solution-soluble. For example, it may have a structure ofpolyamide other than the polyoxazole precursor, a polybenzoxazolestructure, and a precursor for a polyimide or polyimide structure(polyamide acid or polyamide acid ester), together with the polyoxazoleprecursor structure.

A preferred example of the polyamide to be used in the present inventionmay be a phenolic hydroxyl group-containing polyamide having a repeatingunit represented by the general formula (I) above and being alkalineaqueous solution-soluble. The phenolic hydroxyl group-containingpolyamide generally functions as a polyoxazole precursor, preferably apolybenzoxazole precursor. The alkaline aqueous solution refers to analkaline solution of, e.g., tetramethylammonium hydroxide, a metalhydroxide, and an organic amine. A polyoxazole precursor structure suchas the hydroxyl group-containing amide unit represented by the generalformula (I) is subjected to a ring-closing dehydration upon curing andeventually converted into oxazole having excellent heat resistance andmechanical properties as well as excellent electrical properties.

The polyamide used in the present invention preferably has the repeatingunit represented by the general formula (I) above. It is furtherpreferred that the polyamide contains a certain amount or more of the OHgroup-containing amide units, since the solubility of the polyamide inan alkaline aqueous solution is ascribed to an OH group (usually aphenolic hydroxyl group) bonded to the group U.

Specifically, the polyamide is preferably a polyamide represented by thefollowing general formula (IV):

wherein U represents a tetravalent organic group; each of V and Wrepresents a divalent organic group; and each of j and k represents amolar fraction wherein the sum of j and k is 100 mol %, j is 60 to 100mol %, and k is 40 to 0 mol %. In the formula, it is more preferred thatmolar fractions j and k are 80 to 100 mol % and 20 to 0 mol %,respectively.

The component (a) preferably has a molecular weight of 3,000 to 200,000,and more preferably 5,000 to 100,000, in terms of weight averagemolecular weight. The molecular weight referred to herein is a valuemeasured by gel permeation chromatography using a calibration curveobtained with polystyrene standard samples.

There is no particular limitation as to the method for preparing thepolyamide for use in the present invention. For example, the polyamidehaving the repeating unit represented by the general formula (I) abovecan usually be synthesized from a dicarboxylic acid derivative and ahydroxyl group-containing diamine. Specifically, the polyamide may besynthesized by converting a dicarboxylic acid derivative to a dihalidederivative and then reacting the dihalide derivative with the diamine.As the dihalide derivative, preferred is a dichloride derivative.

The dichloride derivative may be synthesized by reacting a dicarboxylicacid derivative with a halogenating agent. Examples of the halogenatingagent for use may include those usually used in acid chlorination of acarboxylic acid, such as thionyl chloride, phosphoryl chloride,phosphorus oxychloride, and phosphorus pentachloride.

Examples of methods for synthesizing a dichloride derivative may includea method in which a dicarboxylic acid derivative and a halogenatingagent are reacted with each other in a solvent, and a method in whichthe reaction is conducted in an excess amount of halogenating agent andthen the excess halogenating agent is distilled off. As the reactionsolvent, for example, N-methyl-2-pyrrolidone, N-methyl-2-pyridone,N,N-dimethylacetamide, N,N-dimethylformamide, toluene, or benzene may beused.

When the reaction is conducted in a solvent, the amount of thehalogenating agent to be used is preferably 1.5 to 3.0 mol, and morepreferably 1.7 to 2.5 mol, relative to the dicarboxylic acid derivative.When the reaction is conducted in the halogenating agent, the amount ofthe halogenating agent used is preferably 4.0 to 50 mol, and morepreferably 5.0 to 20 mol. The reaction temperature is preferably −10 to70° C., and more preferably 0 to 20° C.

It is preferred that the reaction of the dichloride derivative anddiamine is conducted in an organic solvent in the presence of adehydrohalogenating agent. As the dehydrohalogenating agent, an organicbase, such as pyridine or triethylamine, is usually used. As the organicsolvent, for example, N-methyl-2-pyrrolidone, N-methyl-2-pyridone,N,N-dimethylacetamide, or N,N-dimethylformamide may be used. Thereaction temperature is preferably −10 to 30° C., and more preferably 0to 20° C.

In the general formula (I), the tetravalent organic group represented bythe group U is usually a residue derived from dihydroxydiamine whichreacts with dicarboxylic acid to form a polyamide structure, and ispreferably a tetravalent aromatic group. The organic group is preferablya group having 6 to 40 carbon atoms, and more preferably a tetravalentaromatic group having 6 to 40 carbon atoms. The tetravalent aromaticgroup is preferably a residue of diamine having a structure in which allof the four bonding sites are present on the aromatic ring and twohydroxyl groups are positioned at ortho-position of each amine.

Examples of the diamines may include3,3′-diamino-4,4′-dihydroxybiphenyl,4,4′-diamino-3,3′-dihydroxybiphenyl,bis(3-amino-4-hydroxyphenyl)propane,bis(4-amino-3-hydroxyphenyl)propane,bis(3-amino-4-hydroxyphenyl)sulfone,bis(4-amino-3-hydroxyphenyl)sulfone,2,2-bis(3-amino-4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane, and2,2-bis(4-amino-3-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane, althoughnot limited thereto. These compounds may be used individually or incombination.

In the aforementioned formula of the polyamide, the divalent organicgroup represented by the group W is usually a residue derived fromdiamine (excluding the dihydroxydiamine which forms the group U) whichreacts with dicarboxylic acid to form a polyamide structure, and ispreferably a divalent aromatic group or aliphatic group. The organicgroup is preferably a group having 4 to 40 carbon atoms, and morepreferably a divalent aromatic group having 4 to 40 carbon atoms.

Examples of the diamines may include aromatic diamine compounds, such as4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane,4,4′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl sulfide, benzidine,m-phenylenediamine, p-phenylenediamine, 1,5-naphthalenediamine,2,6-naphthalenediamine, bis(4-aminophenoxyphenyl)sulfone,bis(3-aminophenoxyphenyl)sulfone, bis(4-aminophenoxy)biphenyl,bis(4-(4-aminophenoxy)phenyl)ether, and 1,4-bis(4-aminophenoxy)benzene,and diamines having a silicone group, such as LP-7100, X-22-161AS,X-22-161A, X-22-161B, X-22-161C, and X-22-161E (trade names; eachmanufactured by Shin-Etsu Chemical Co., Ltd.), although not limitedthereto. These compounds may be used individually or in combination.

In the general formula (I), the divalent organic group represented bythe group V is a residue derived from dicarboxylic acid which reactswith diamine to form a polyamide structure, and is preferably a divalentaromatic group. The organic group is preferably a group having 6 to 40carbon atoms, and more preferably a divalent aromatic group having 6 to40 carbon atoms. The divalent aromatic group preferably has a structurein which all of the two bonding sites are present on the aromatic ring.

Examples of the dicarboxylic acids may include aromatic dicarboxylicacids, such as isophthalic acid, terephthalic acid,2,2-bis(4-carboxyphenyl)-1,1,1,3,3,3-hexafluoropropane,4,4′-dicarboxybiphenyl, 4,4′-dicarboxydiphenyl ether,4,4′-dicarboxytetraphenylsilane, bis(4-carboxyphenyl) sulfone,2,2-bis(p-carboxyphenyl)propane, 5-tert-butylisophthalic acid,5-bromoisophthalic acid, 5-fluoroisophthalic acid, 5-chloroisophthalicacid, and 2,6-naphthalenedicarboxylic acid; and aliphatic dicarboxylicacids, such as 1,2-cyclobutanedicarboxylic acid,1,4-cyclohexanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid,oxalic acid, malonic acid, and succinic acid, although not limitedthereto. These compounds may be used individually or in combination.

As mentioned above, the component (a), i.e. polyamide in the presentinvention, may be a polyoxazole precursor having a polyimide precursorstructure. A specific example thereof may be a polyamide having arepeating unit represented by the following general formula (VI):

wherein Y represents a di- to octavalent organic group having at leasttwo carbon atoms; Z represents a di- to hexavalent organic group havingat least two carbon atoms; R⁷ represents hydrogen or an organic grouphaving 1 to 20 carbon atoms; l is an integer of 0 to 2; each of g and his an integer of 0 to 4; and i is the number of the repeating units,preferably an integer of 10 to 100,000, with the proviso that l in atleast part of the repeating units is 1 or 2, and that the sum of g and hin at least part of the repeating units is equal to or more than 1.

Examples of preferred structures of Y and Z may be those shown below. Ineach structure of Y or Z, the bonding site to another atom is present onthe aromatic ring.

In the above structures, the bonding site of each of Y and Z to anotheratom is usually present on the aromatic ring. It is preferred thatbonding sites to an amide group and a carboxyl group are present on thearomatic ring at the end of each structure. In the structure in which Xand Y have an amide linkage, it is preferred that a hydroxyl group (OH)is present on the aromatic ring to which a nitrogen atom is bonded, andpositioned at ortho-position of the nitrogen atom, so that the structurecan form a benzoxazole ring at the later stage of reaction.

Preferred examples of R⁷s may include a hydrogen atom, a methyl group,an ethyl group, an isopropyl group, a t-butyl group, a n-butyl group, acyclohexyl group, a phenyl group, a p-hydroxybenzyl group, and atetrahydropyranyl group.

With respect to the method for preparing the polyoxazole precursorhaving a polyimide precursor structure, there is no particularlimitation. However, it is preferred that a polyimide precursor isprepared using, for example, as diamine and/or tetracarboxylicdianhydride which are materials for a polyimide precursor, diamineand/or tetracarboxylic dianhydride having in their structures astructure capable of forming an oxazole ring (hereinafter, they may bereferred to, respectively, as “diamine (i)” and “tetracarboxylicdianhydride (ii)”).

As examples of diamine (i) and tetracarboxylic dianhydride (ii), therecan be mentioned the following compounds.Diamine (i)

Tetracarboxylic dianhydride (ii)

Examples of diamines to be used in combination with tetracarboxylicdianhydride (ii) may include diamine (i) and the diamines mentionedabove in connection with U or W in the general formula (I) above.Examples of tetracarboxylic dianhydrides to be used in combination withdiamine (i) may include tetracarboxylic dianhydride (ii), andpyromellitic dianhydride, biphenyltetracarboxylic dianhydride,benzophenone tetracarboxylic dianhydride, and oxydiphthalic dianhydride.

The component (b), i.e., an o-quinonediazide compound used in thepresent invention is a sensitizer, which generates carboxylic acid uponirradiation with light and increases the solubility of the irradiatedportion of the composition in an alkaline aqueous solution. Such ano-quinonediazide compound may be obtained by, for example, subjecting ano-quinonediazidosulfonyl chloride to condensation reaction in thepresence of a dehydrochlorinating agent with another compound such as ahydroxy compound and an amino compound. Examples of theo-quinonediazidosulfonyl chlorides may includebenzoquinone-1,2-diazido-4-sulfonyl chloride,naphthoquinone-1,2-diazido-5-sulfonyl chloride, andnaphthoquinone-1,2-diazido-4-sulfonyl chloride.

Examples of the hydroxy compound may include hydroquinone, resorcinol,pyrogallol, bisphenol A, bis(4-hydroxyphenyl)methane,2,2-bis(4-hydroxyphenyl)hexafluoropropane, 2,3,4-trihydroxybenzophenone,2,3,4,4′-tetrahydroxybenzophenone, 2,2′,4,4′-tetrahydroxybenzophenone,2,3,4,2′,3′-pentahydroxybenzophenone,2,3,4,3′,4′,5′-hexahydroxybenzophenone,bis(2,3,4-trihydroxyphenyl)methane, bis(2,3,4-trihydroxyphenyl)propane,4b,5,9b,10-tetrahydro-1,3,6,8-tetrahydroxy-5,10-dimethylindeno[2,1-a]indene,tris(4-hydroxyphenyl)methane, and tris(4-hydroxyphenyl)ethane.

Examples of amino compounds may include p-phenylenediamine,m-phenylenediamine, 4,4′-diaminodiphenyl ether,4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl sulfone,4,4′-diaminodiphenyl sulfide, o-aminophenol, m-aminophenol,p-aminophenol, 3,3′-diamino-4,4′-dihydroxybiphenyl,4,4′-diamino-3,3′-dihydroxybiphenyl,bis(3-amino-4-hydroxyphenyl)propane,bis(4-amino-3-hydroxyphenyl)propane,bis(3-amino-4-hydroxyphenyl)sulfone,bis(4-amino-3-hydroxyphenyl)sulfone,bis(3-amino-4-hydroxyphenyl)hexafluoropropane, andbis(4-amino-3-hydroxyphenyl)hexafluoropropane.

It is preferred that the o-quinonediazidosulfonyl chloride and thehydroxy compound and/or the amino compound are incorporated so that thesum of the hydroxyl group and the amino group becomes 0.5 to 1equivalent amount, relative to 1 mol of o-quinonediazidosulfonylchloride. A preferred dehydrochlorinating agent/o-quinonediazidosulfonylchloride ratio is in the range of from 0.95/1 to 1/0.95. The reactiontemperature is preferably 0 to 40° C., and the reaction time ispreferably 1 to 10 hours.

A solvent for the reaction may be dioxane, acetone, methyl ethyl ketone,tetrahydrofuran, diethyl ether, or N-methylpyrrolidone. Examples ofdehydrochlorinating agents may include sodium carbonate, sodiumhydroxide, sodium hydrogencarbonate, potassium carbonate, potassiumhydroxide, trimethylamine, triethylamine, and pyridine.

In the positive photosensitive resin composition of the presentinvention, the amount of the component (b) incorporated is preferably 5to 100 parts by weight, more preferably 8 to 40 parts by weight,relative to 100 parts by weight of the component (a), from the viewpointof achieving appropriate solubility difference between the exposedportion and the unexposed portion and from the viewpoint of acceptablerange of the sensitivity.

The component (c) used in the present invention is a latent acidgenerator which generates acid upon heating. The latent acid generatorin the present invention preferably has a heat decomposition startingtemperature of 50 to 270° C. Specifically, the latent acid generatorpreferably has a 1% weight reduction temperature of 50 to 270° C. or a5% weight reduction temperature of 60 to 300° C., as measured bythermogravimetric analysis (TG). The latent acid generator morepreferably has a heat decomposition starting temperature of 140 to 250°C. since such an acid generator generates no acid during the prebake andhence it does not adversely affect the light-sensitivity properties.Specifically, the latent acid generator preferably has a 1% weightreduction temperature of 140 to 250° C. or a 5% weight reductiontemperature of 170 to 265° C., as measured by thermogravimetric analysis(TG).

Acid generated from the latent acid generator is preferably strong acid.Preferable examples thereof may include arylsulfonic acid, such asp-toluenesulfonic acid or benzenesulfonic acid; perfluoroalkylsulfonicacid, such as camphorsulfonic acid, trifluoromethanesulfonic acid, ornonafluorobutanesulfonic acid; or alkylsulfonic acid, such asmethanesulfonic acid, ethanesulfonic acid, or butanesulfonic acid. Theabove acid efficiently functions as a catalyst for the dehydrationreaction and cyclization of a phenolic hydroxyl group-containingpolyamide structure of the polybenzoxazole precursor. In contrast, anacid generator that generates hydrochloric acid, bromic acid, iodicacid, or nitric acid, which has weak acidity and easily volatilizes byheating, is considered to have almost no effect on the cyclodehydrationreaction of the polybenzoxazole precursor, making it difficult tosatisfactorily obtain the effect of the present invention.

The acid is added to the positive photosensitive resin composition ofthe present invention as a latent acid generator in the form of an oniumsalt or a covalent bond in, e.g., imide sulfonate.

Preferred examples of the onium salts may include diaryliodonium salts,such as a diphenyliodonium salt; di(alkylaryl)iodonium salts, such as adi(t-butylphenyl)iodonium salt; trialkylsulfonium salts, such as atrimethylsulfonium salt; dialkylmonoarylsulfonium salts, such as adimethylphenylsulfonium salt; and diarylmonoalkylsulfonium salts, suchas a diphenylmethylsulfonium salt. These salts have a decompositionstarting temperature in the range of from 150 to 250° C., and henceefficiently decompose in the cyclodehydration reaction of apolybenzoxazole precursor at a temperature equal to or lower than 280°C. In contrast, a triphenylsulfonium salt is not preferred as a latentacid generator in the present invention. A triphenylsulfonium salt hashigh thermal stability and generally has a decomposition temperaturehigher than 300° C., and therefore it does not decompose in thecyclodehydration reaction of a polybenzoxazole precursor at atemperature equal to or lower than 280° C., which indicates that thetriphenylsulfonium salt does not satisfactorily function as a catalystfor the cyclodehydration.

From the above point of view, as the onium salt which serves as thelatent acid generator, preferred is, for example, a diaryliodonium salt,a di(alkylaryl)iodonium salt, a trialkylsulfonium salt, adialkylmonoarylsulfonium salt, or a diarylmonoalkylsulfonium salt ofarylsulfonic acid, camphorsulfonic acid, perfluoroalkylsulfonic acid, oralkylsulfonic acid. Specifically, as preferred examples, there may bementioned di(t-butylphenyl)iodonium paratoluenesulfonate (1% weightreduction temperature: 180° C.; 5% weight reduction temperature: 185°C.), di(t-butylphenyl)iodonium trifluoromethanesulfonate (1% weightreduction temperature: 151° C.; 5% weight reduction temperature: 173°C.), trimethylsulfonium trifluoromethanesulfonate (1% weight reductiontemperature: 255° C.; 5% weight reduction temperature: 278° C.),dimethylphenylsulfonium trifluoromethanesulfonate (1% weight reductiontemperature: 186° C.; 5% weight reduction temperature: 214° C.),diphenylmethylsulfonium trifluoromethanesulfonate (1% weight reductiontemperature: 154° C.; 5% weight reduction temperature: 179° C.),di(t-butylphenyl)iodonium nonafluorobutanesulfonate, diphenyliodoniumcamphorsulfonate, diphenyliodonium ethanesulfonate,dimethylphenylsulfonium benzenesulfonate, and diphenylmethylsulfoniumtoluenesulfonate.

As imide sulfonate, naphthoylimide sulfonate is desired. In contrast,phthalimide sulfonate has poor thermal stability and generates acidbefore the curing reaction, lowering the storage stability and thus notbeing preferable. Specific preferred examples of naphthoylimidesulfonate may include 1,8-naphthoylimide trifluoromethylsulfonate (1%weight reduction temperature: 189° C.; 5% weight reduction temperature:227° C.) and 2,3-naphthoylimide trifluoromethylsulfonate (1% weightreduction temperature: 185° C.; 5% weight reduction temperature: 216°C.)

As the component (c), a compound having an R¹R²C═N—O—SO₂—R structure,such as the one represented by the chemical formula given below (1%weight reduction temperature: 204° C.; 5% weight reduction temperature:235° C.), may be used. Examples of R herein may include aryl groups,such as a p-methylphenyl group and a phenyl group; alkyl groups, such asa methyl group, an ethyl group, and an isopropyl group; andperfluoroalkyl groups, such as a trifluoromethyl group and anonafluorobutyl group. Examples of R¹ may include a cyano group, andexamples of R² may include a methoxyphenyl group and a phenyl group.

As the component (c), a compound having an amide structure —HN—SO₂—R,such as the one represented by the chemical formula given below (1%weight reduction temperature: 104° C.; 5% weight reduction temperature:270° C.), may be used. Examples of R herein may include alkyl groups,such as a methyl group, an ethyl group, and a propyl group; aryl groups,such as a methylphenyl group and a phenyl group; and perfluoroalkylgroups, such as a trifluoromethyl group and a nonafluorobutyl group.Examples of groups to which —HN—SO₂—R is bonded may include2,2′-bis(4-hydroxyphenyl)hexafluoropropane,2,2′-bis(4-hydroxyphenyl)propane, and di(4-hydroxyphenyl)ether.

As the component (c) in the present invention, there may be used a saltformed from a strong acid and a base, which salt is not involved inonium salts. As the strong acid, preferred is, for example, arylsulfonicacid, such as p-toluenesulfonic acid or benzenesulfonic acid;perfluoroalkylsulfonic acid, such as camphorsulfonic acid,trifluoromethanesulfonic acid, or nonafluorobutanesulfonic acid; oralkylsulfonic acid, such as methanesulfonic acid, ethanesulfonic acid,or butanesulfonic acid. As the base, preferred is, for example,alkylpyridine, such as pyridine or 2,4,6-trimethylpyridine;N-alkylpyridine, such as 2-chloro-N-methylpyridine; or halogenatedN-alkylpyridine. More specifically, as preferred examples, there may bementioned pyridine p-toluenesulfonate (1% weight reduction temperature:147° C.; 5% weight reduction temperature: 190° C.), a salt composed ofdibenzyl L-aspartate and p-toluenesulfonic acid (1% weight reductiontemperature: 202° C.; 5% weight reduction temperature: 218° C.),2,4,6-trimethylpyridine p-toluenesulfonate, and 1,4-dimethylpyridinep-toluenesulfonate. These compounds may decompose in thecyclodehydration reaction of a polybenzoxazole precursor at atemperature equal to or lower than 280° C. and may function as acatalyst.

The amount of the component (c) incorporated is preferably 0.1 to 30parts by weight, more preferably 0.2 to 20 parts by weight, furtherpreferably 0.5 to 10 parts by weight, relative to 100 parts by weight ofthe component

When the component (d), i.e., a compound having a phenolic hydroxylgroup optionally used in the present invention is added to thecomposition, the solubility of the exposed portion may be increased inthe development with an alkaline aqueous solution, thus improving thesensitivity. Further, upon curing a film having a pattern formed, thefilm may be prevented from melting. With respect to the compound havinga phenolic hydroxyl group to be used in the present invention, there isno particular limitation. However, when a compound having too large amolecular weight is used, the dissolution promotion effect for theexposed portion is lowered and therefore, generally, the compoundpreferably has a molecular weight equal to or less than 1,500.Especially preferred is a compound of the general formula (II) below,which has a good balance between the dissolution promotion effect forthe exposed portion and the effect of preventing the film being curedfrom melting.

wherein X represents a single bond or a divalent organic group, each ofR³ to R⁶ independently represents a hydrogen atom or a monovalentorganic group, each of m and n is independently an integer of 1 to 3,and each of p and q is independently an integer of 0 to 4.

Examples of divalent groups represented by X in the general formula (II)above may include alkylene groups having 1 to 10 carbon atoms, such as amethylene group, an ethylene group, and a propylene group; alkylidenegroups having 2 to 10 carbon atoms, such as an ethylidene group; arylenegroups having 6 to 30 carbon atoms, such as a phenylene group; a groupobtained by replacing part of or all of the hydrogen atoms in the abovehydrocarbon group by a halogen atom or halogen atoms, such as a fluorineatom; a sulfonic group; a carbonyl group; an ether linkage; a thioetherlinkage; and an amide linkage, and preferred examples may includedivalent organic groups represented by the following general formula(V):

wherein each X′ is independently selected from a single bond, analkylene group (having, for example, 1 to 10 carbon atoms), analkylidene group (having, for example, 2 to 10 carbon atoms), a groupobtained by replacing part of or all of the hydrogen atoms in the abovegroup by a halogen atom or halogen atoms, a sulfonic group, a carbonylgroup, an ether linkage, a thioether linkage, and an amide linkage; R⁹is a hydrogen atom, a hydroxyl group, an alkyl group, or a haloalkylgroup, and, when a plurality of R⁹'s are present, they may be the sameor different; and m is 1 to 10.

Further preferred examples may include a compound of the general formula(II) above wherein the group represented by X is the following generalformula (III):

wherein each of two A's independently represents a hydrogen atom or analkyl group having 1 to 10 carbon atoms, and optionally has any one ofan oxygen atom and a fluorine atom or both, since the compound has morepreferable effect.

In the positive photosensitive resin composition of the presentinvention, the amount of the component (d) incorporated is preferably 1to 30 parts by weight, more preferably 3 to 25 parts by weight, relativeto 100 parts by weight of the component (a), from the viewpoint ofacceptable range of the development time and the unexposed portionresidual ratio.

The positive photosensitive resin composition of the present inventionmay comprise a solvent as an optional component. Examples of solventsusually used may include γ-butyrolactone, ethyl lactate, propyleneglycol monomethyl ether acetate, benzyl acetate, n-butyl acetate,ethoxyethyl propionate, methyl 3-methoxypropionate,N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide,dimethyl sulfoxide, hexamethyl phophorylamide, tetramethylene sulfone,diethyl ketone, diisobutyl ketone, and methyl amyl ketone.

These solvents may be used individually or in combination. With respectto the amount of the solvent used, there is no particular limitation.However, generally, the amount is preferably controlled so that thecontent of the solvent in the composition becomes 20 to 90% by weight.

In the positive photosensitive resin composition of the presentinvention, a compound for inhibiting dissolution of the component (a) inan alkaline aqueous solution may be further added. Specific examples ofcompounds for inhibiting dissolution of the component (a) may includediphenyliodonium nitrate, bis(p-tert-butylphenyl)iodonium nitrate,diphenyliodonium bromide, diphenyliodonium chloride, anddiphenyliodonium iodide.

The above compounds generate acid which easily volatilizes, and hencehave no effect on the cyclodehydration reaction of a polybenzoxazoleprecursor. However, they effectively inhibit the dissolution andcontribute to controlling of the thickness of the residual film ordevelopment time. From the viewpoint of acceptable range of thesensitivity and the development time, the amount of the componentincorporated is preferably 0.01 to 15 parts by weight, more preferably0.01 to 10 parts by weight, further preferably 0.05 to 3 parts byweight, relative to 100 parts by weight of the component (a).

The positive photosensitive resin composition of the present inventionmay contain an organosilane compound or an aluminum chelate compound forimproving the adhesion of a cured film to a substrate. Examples oforganosilane compounds may include vinyltriethoxysilane,γ-glycidoxypropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane,ureidopropyltriethoxysilane, methylphenylsilanediol,ethylphenylsilanediol, n-propylphenylsilanediol,isopropylphenylsilanediol, n-butylphenylsilanediol,isobutylphenylsilanediol, tert-butylphenylsilanediol,diphenylsilanediol, ethylmethylphenylsilanol,n-propylmethylphenylsilanol, isopropylmethylphenylsilanol,n-butylmethylphenylsilanol, isobutylmethylphenylsilanol,tert-butylmethylphenylsilanol, ethyl-n-propylphenylsilanol,ethylisopropylphenylsilanol, n-butylethylphenylsilanol,isobutylethylphenylsilanol, tert-butylethylphenylsilanol,methyldiphenylsilanol, ethyldiphenylsilanol, n-propyldiphenylsilanol,isopropyldiphenylsilanol, n-butyldiphenylsilanol,isobutyldiphenylsilanol, tert-butyldiphenylsilanol, phenylsilanetriol,1,4-bis(trihydroxysilyl)benzene, 1,4-bis(methyldihydroxysilyl)benzene,1,4-bis(ethyldihydroxysilyl)benzene,1,4-bis(propyldihydroxysilyl)benzene,1,4-bis(butyldihydroxysilyl)benzene,1,4-bis(dimethylhydroxysilyl)benzene,1,4-bis(diethylhydroxysilyl)benzene,1,4-bis(dipropylhydroxysilyl)benzene, and1,4-bis(dibutylhydroxysilyl)benzene. Examples of aluminum chelatecompounds may include tris(acetylacetonato)aluminum and acetyl acetatealuminum diisopropylate. When the adhesion improving agent is used, theamount of the agent incorporated is preferably 0.1 to 20 parts byweight, more preferably 0.5 to 10 parts by weight, relative to 100 partsby weight of the component (a).

In the positive photosensitive resin composition of the presentinvention, for improving the spreadability, for example, preventingstriation (unevenness of thickness), or improving the developmentproperties, an appropriate surfactant or leveling agent may be added.Examples of the surfactants or leveling agents may includepolyoxyethylene lauryl ether, polyoxyethylene stearyl ether,polyoxyethylene oleyl ether, and polyoxyethylene octylphenol ether, andexamples of commercially available products may include Megaface F171,F173, and R-08 (trade names; manufactured by Dainippon Ink & ChemicalsIncorporated), Fluorad FC430, FC431 (trade names; manufactured bySumitomo 3M), and organosiloxane polymers KP341, KBM303, KBM403, andKBM803 (trade names; manufactured by Shin-Etsu Chemical Co., Ltd.).

With the positive photosensitive resin composition of the presentinvention, a pattern of polyoxazole may be formed through a step ofapplying the composition onto a supporting substrate and drying thecomposition, a step of exposing the resultant film to a predeterminedpattern, a step of developing the film, and an optional step ofsubjecting the film to heating treatment. In the step of applying thecomposition onto a supporting substrate and drying the composition, thephotosensitive resin composition of the present invention is appliedonto a supporting substrate, such as a glass substrate, a semiconductor,a metal oxide insulator (e.g., TiO₂ or SiO₂), or silicon nitride, byspin coating using, e.g., a spinner, and then the applied composition isdried using a hotplate or an oven.

In the subsequent exposure step, the coating film formed of thephotosensitive resin composition on the supporting substrate isirradiated through a mask with a ray of active light, such asultraviolet light, visible light, or radiation. In the development step,the exposed portion is removed using a developer to obtain a pattern.Preferred examples of developers may include alkaline aqueous solutionsof sodium hydroxide, potassium hydroxide, sodium silicate, ammonia,ethylamine, diethylamine, triethylamine, triethanolamine, ortetramethylammonium hydroxide. The aqueous solution preferably has abase concentration of 0.1 to 10% by weight. The developer may contain analcohol or a surfactant. It may be added preferably in an amount of 0.01to 10 parts by weight, more preferably 0.1 to 5 parts by weight,relative to 100 parts by weight of the developer.

In the subsequent heating treatment step, the pattern obtained ispreferably subjected to heating treatment at a temperature equal to orlower than 280° C., more preferably 150 to 280° C. to form a pattern ofheat-resistant polyoxazole having an oxazole ring and another functionalgroup. In the heating treatment step, a more preferred temperature ofthe heating treatment is 220 to 260° C. It is preferred that the heatingtreatment is conducted in nitrogen atmosphere, which may prevent thephotosensitive resin composition film from oxidation. In the abovetemperature range, the cyclodehydration reaction efficiently proceedswith minimum damages on the substrate and the device. Therefore, byusing the method for forming a pattern of the present invention, adevice can be produced in high yield. In addition, this leads to savingson energy consumed in the process.

In the heating treatment in the present invention, an ordinary ovenfilled with nitrogen, or a microwave curing apparatus or a variablefrequency microwave curing apparatus may be used. By using suchapparatus, only the photosensitive resin composition film may beeffectively heated while maintaining the temperature of the substrate ordevice at, for example, a temperature equal to or lower than 250° C.

Studies on the ring-closing dehydration of a polyimide precursor usingmicrowaves are disclosed in, for example, JP-2587148 B and JP-3031434 B.Further, U.S. Pat. No. 5,738,915 has proposed a method in which, in thering-closing dehydration of a polyimide precursor thin film usingmicrowaves, the film is irradiated with microwaves while changing thefrequency in a short cycle to prevent the polyimide thin film orsubstrate from damages.

When the film is irradiated with a pulse of microwave while changing thefrequency, standing waves can be avoided, so that the surface of thesubstrate can be advantageously heated uniformly. When a substratecomprising a metal wiring in the electronic part (mentioned below) isirradiated with a pulse of microwave while changing the frequency, theoccurrence of, e.g., electric discharge from a metal can be prevented,so that the electronic part can be advantageously protected frombreakage due to, e.g., electric discharge.

The frequency of the microwave to be employed for the ring-closingdehydration of the polyamide in the positive photosensitive resincomposition of the present invention may be in the range of from 0.5 to20 GHz. In this range, from a practical point of view, the frequency ispreferably in the range of from 1 to 10 GHz, more preferably 2 to 9 GHz.

It is desired that the frequency of the microwave for irradiation iscontinuously changed, but the frequency may actually be changedstepwise. Upon such a stepwise frequency changing, the irradiation timeof the microwave of a certain frequency is preferably as short aspossible, for minimizing the standing wave and the electric dischargefrom the metal. The irradiation time of a microwave of single frequencyis preferably 1 msec. or less, especially preferably 100 μsec. or less.

The power of the microwave for irradiation may vary depending on thesize of the apparatus to be used or the amount of the material to beheated, but the power is generally in the range of from 10 to 2,000 W.In this range, from a practical point of view, the power is preferably100 to 1,000 W, more preferably 100 to 700 W, most preferably 100 to 500W. When the power is 10 W or less, it may be difficult to heat amaterial in a short time, and, when the power is 2,000 W or more,too-rapid temperature elevation is likely to occur.

The ring-closing dehydration of the polyamide in the positivephotosensitive resin composition of the present invention is preferablyperformed at a low temperature as mentioned above for preventing thepolyoxazole thin film or substrate from damages during the ring-closingdehydration. In the present invention, the temperature for ring-closingdehydration of the polyamide in the positive photosensitive resincomposition is preferably equal to or lower than 280° C., morepreferably equal to or lower than 250° C., most preferably equal to orlower than 210° C. The temperature of the substrate may be measured by aknown method such as those using infrared or a thermocouple of, e.g.,GaAs.

It is preferred that the microwave used in the ring-closing dehydrationof the polyamide in the positive photosensitive resin composition of thepresent invention is irradiated as a pulse form by repeating “on/off”operations. Such an irradiation of the microwave in the pulse form mayachieve stable heating at an adjusted temperature, thus making itpossible to prevent the polyoxazole thin film or substrate from damages.The time of one pulse of microwave for irradiation may vary depending onthe conditions, but the time is generally 10 sec. or shorter.

The time of the ring-closing dehydration of the polyamide in thepositive photosensitive resin composition of the present inventionrefers to a period of time until the ring-closing dehydration reactionsatisfactorily proceeds. Preferably, the time is generally 5 hours orless from the viewpoint of achieving appropriate operation efficiency.The atmosphere for the ring-closing dehydration may be selected from airand an inert atmosphere of, e.g., nitrogen.

Thus, irradiation of the substrate having a layer of the positivephotosensitive resin composition of the present invention with amicrowave under the above-mentioned conditions results in ring-closingdehydration of the polyamide contained in the positive photosensitiveresin composition of the present invention. The polyoxazole thin filmobtainable by this ring-closing dehydration at a low temperature usingthe microwave will have physical properties comparable with those of thefilm obtained by a ring-closing dehydration process at a hightemperature using a heat diffusion oven.

The positive photosensitive resin composition of the present inventionmay be used in an electronic part, such as a semiconductor device or amultilayer wiring board, and specifically may be used for forming asurface protecting film or interlayer insulating layer in asemiconductor device, or forming an interlayer insulating layer in amultilayer wiring board. As to the semiconductor device in the presentinvention, there is no particular limitation as long as it has thesurface protecting film or interlayer insulating layer formed using theaforementioned composition, and may have a variety of structures.

One example of a fabrication process for the semiconductor device in thepresent invention will be described below. FIGS. 1 to 5 are views of thefabrication process for a semiconductor device having a multilayerwiring structure. FIGS. 1 to 5 are a series of the first through fifthsteps, respectively. In FIGS. 1 to 5, semiconductor substrate 1 composedof, e.g., a Si substrate having a circuit element is covered withprotective film 2 composed of, e.g., a silicon oxide film, leaving apredetermined portion of the circuit element uncovered. First conductorlayer 3 is formed on the uncovered part of the circuit element. Film 4composed of, e.g., a polyimide resin is formed as an interlayerinsulating layer on the semiconductor substrate by, for example, a spincoating process (first step).

Photosensitive resin layer 5 composed of, e.g., chlorinated rubber orphenolic novolak is then formed on interlayer insulating layer 4 by aspin coating process, and windows 6A are formed by a knownphotolithography technique so that predetermined portions of interlayerinsulating layer 4 are uncovered (second step). Interlayer insulatinglayer 4 within windows 6A is selectively etched by a dry etching methodusing gas of oxygen or carbon tetrafluoride, to form windows 6B.Photosensitive resin layer 5 is then completely removed using an etchingsolution such that first conductor layer 3 within windows 6B is notetched but photosensitive resin layer 5 is selectively etched (thirdstep).

Second conductor layer 7 is then formed using a known photolithographytechnique to achieve complete electrical connection with first conductorlayer 3 (fourth step). If a multilayer wiring structure composed ofthree or more layers is desired, the aforementioned series of steps maybe repeated for forming each layer.

Surface protecting film 8 is subsequently formed. In this example ofFIGS. 1 to 5, the surface protecting film is formed using theaforementioned photosensitive resin composition. The photosensitiveresin composition is first applied by a spin coating process and dried,and irradiated with light through a mask having a pattern for formingwindows 6C at predetermined positions. The resultant film is thendeveloped using an alkaline aqueous solution to form a pattern. The filmis then subjected to heating treatment, to obtain surface protectingfilm layer (polybenzoxazole film) 8 (fifth step). Surface protectingfilm layer (polybenzoxazole film) 8 protects the conductor layer from anexternal stress or α-ray, and thus the resultant semiconductor devicehas excellent reliability. The photosensitive resin film that hasexposed to the light may be heated prior to the development (PEB).

In the present invention, the step of heating treatment for curing thepolyoxazole film may be performed at a temperature equal to or lowerthan 280° C., which conventionally needs to be 300° C. or higher. Thephotosensitive resin composition of the present invention satisfactorilyundergoes a cyclodehydration reaction in the curing even at atemperature equal to or lower than 280° C. Therefore the resultant filmhas physical properties (e.g., elongation, water absorption, weightreduction temperature, and outgas) comparable with those of the filmcured at 300° C. or higher. The temperature for the process can belowered and hence a defect of the device due to heat can be reduced,whereby a semiconductor device having excellent reliability can beobtained with a high yield.

In the above example, the interlayer insulating layer may also be formedusing the photosensitive resin composition of the present invention.

As a preferred example of an electronic part comprising an electronicdevice having a surface protecting film or interlayer insulating layerobtained using the photosensitive resin composition of the presentinvention, there can be mentioned an MRAM having a low heat resistance.That is, the photosensitive resin composition of the present inventionis advantageously used as a surface protecting film for MRAM.

In addition to the MRAM, a polymer memory (polymer ferroelectric RAM(PFRAM)) or a phase change memory (phase change RAM (PCRAM) or ovonicsunified memory (OUM)), which are promising memories of next generation,may also employ therein a new material having a low heat resistance, ascompared to a conventional memory. Thus, the photosensitive resincomposition of the present invention is also preferable as a surfaceprotecting film for such devices.

EXAMPLES

The present invention will be explained in further detail with referenceto the following Examples. Note that the present invention is notlimited by the Examples.

Examples 1 to 14 Synthesis Example 1 Synthesis of PolybenzoxazolePrecursor

15.48 g of 4,4′-diphenyl ether dicarboxylic acid and 90 g ofN-methylpyrrolidone were changed into a 0.5-liter flask having a stirrerand a thermometer. The flask was cooled to 5° C., and 12.64 g of thionylchloride was then added dropwise thereto. Reaction was performed for 30minutes for obtaining a solution of 4,4′-diphenyl ether dicarboxylicacid chloride. Separately, 87.5 g of N-methylpyrrolidone was changedinto a 0.5-liter flask having a stirrer and a thermometer, and 18.30 gof bis(3-amino-4-hydroxyphenyl)hexafluoropropane was added to the flaskand dissolved in the solution by stirring. 8.53 g of pyridine was addedthereto. While maintaining the temperature at 0 to 5° C., the solutionof 4,4′-diphenyl ether dicarboxylic acid chloride obtained in theaforementioned procedure was added dropwise thereto over 30 minutes, andthe resultant mixture was stirred for another 30 minutes. The solutionthus obtained was poured into 3 liters of water, and the resultingprecipitate was collected and washed with pure water three times,followed by vacuum drying, to obtain polyhydroxyamide (polybenzoxazoleprecursor) (hereinafter referred to as “polymer I”). Polymer I had aweight average molecular weight of 14,580 and a molecular weightdistribution of 1.6, as measured by GPC using a calibration curveobtained from standard polystyrene.

Synthesis Example 2

Synthesis was conducted under the same conditions as in SynthesisExample 1 except that 20 mol % of 4,4′-diphenyl ether dicarboxylic acidwas replaced with cyclohexane-1,4-dicarboxylic acid. Thepolyhydroxyamide thus obtained (hereinafter referred to as “polymer II”)had a weight average molecular weight of 18,580 and a molecular weightdistribution of 1.5, as measured by GPC using a calibration curveobtained from standard polystyrene.

Evaluation of Sensitivity Properties

100 parts by weight of the polybenzoxazole precursor (the component (a))was mixed with the component (b) as a sensitizer, the latent acidgenerator (c) which generates acid upon heating, the compound (d) havinga phenolic hydroxyl group, and the solvent (e) at predetermined amountsshown in the Table 1 below. 10 parts by weight of a 50% methanolsolution of ureidopropyltriethoxysilane as an adhesion promoter wasfurther added thereto. The resulting solution was subjected topressurized filtration using a 3 μm pore Teflon® filter, to obtain asolution of a photosensitive resin composition. TABLE 1 Component Compo-Compo- Compo- Compo- (a) nent (b) nent (c) nent (d) nent (e) Example 1Polymer I B1(10) C1(2.5) D1(10) E1(160) Example 2 Polymer II B1(11)C2(2) D1(10) E1(160) Example 3 Polymer II B1(10) C3(3) D1(10) E1(160)Example 4 Polymer II B2(10) C4(2.5) D2(10) E1(160) Example 5 Polymer IB2(10) C5(1.5) D2(10) E1(160) Example 6 Polymer I B2(10) C6(1.5) D2(10)E1(160) Example 7 Polymer I B3(12) C7(4) D1(8) E1(160) Example 8 PolymerI B3(11) C8(2) D1(8) E1(160) Example 9 Polymer I B3(10) C9(3) D1(8)E1(160) Example 10 Polymer I B1(11) C10(2.5) D2(10) E1(160) Example 11Polymer I B1(11) C11(2.5) D2(10) E1(160) Example 12 Polymer I B1(11)C12(2) D2(10) E2(160) Example 13 Polymer I B3(12) C13(1.5) D1(10)E2(160) Example 14 Polymer I B3(12) C14(8) D1(10) E2(160)In the Table, the figure in each pair of parentheses represents theamount of each component in terms of parts by weight relative to 100parts by weight of the polymer.

Chemical formulae of the components (b) and components (c) in Table 1are as follows:

As the component (e), E1 stands for γ-butyrolactone/propylene glycolmonomethyl ether acetate=90/10 (parts by weight), and E2 stands forγ-butyrolactone/N-methyl-2-pyrrolidone=50/50 (parts by weight).

Each of the solutions obtained by the aforementioned procedure wasapplied onto a silicon wafer by spin coating and heated at 120° C. for 3minutes, to form a coating film having a thickness of 11 to 13 μm. Thefilm was then subjected to reduction projection exposure with i-line(365 nm) through a mask using an i-line stepper (FPA-3000iW;manufactured by CANON INC.). After the exposure, the resulting film wasdeveloped using a 2.38% aqueous solution of tetramethylammoniumhydroxide so that the thickness of the residual film became about 70 to90% of the initial thickness. The pattern was then rinsed with water,and examined for measuring minimum exposure energy required for formingthe pattern and resolution. The results are shown in Table 2 below.TABLE 2 Sensitivity Residual film Resolution (mJ/cm²) ratio (%) (μm)Example 1 210 76 2 Example 2 250 77 2 Example 3 280 82 3 Example 4 26080 3 Example 5 300 76 3 Example 6 200 78 2 Example 7 280 80 2 Example 8290 81 2 Example 9 350 82 2 Example 10 210 76 2 Example 11 230 79 2Example 12 280 80 3 Example 13 400 78 3 Example 14 290 76 3

Furthermore, each of the solutions obtained by the aforementionedprocedure was applied onto a silicon wafer by spin coating, and heatedat 120° C. for 3 minutes, to form a coating film having a thickness of15 μm. The film was then heated in a nitrogen atmosphere in an inert gasoven at 150° C. for 30 minutes, and then further heated at 300° C. for 1hour or, alternatively, at 250° C. for 1 hour to obtain a cured film.Subsequently, the cured film was peeled off using an aqueous solution ofhydrofluoric acid, and washed with water and dried. Physical propertiesof the film, i.e., glass transition temperature (Tg), water absorption,elongation (measured by means of a tensile tester), and 5% weightreduction temperature were measured. The results are shown in Table 3below. TABLE 3 Curing Water 5% Weight temperature Tg Elongationabsorption temperature (° C.) (° C.) (%) (%) (° C.) Example 1 250 285 440.63 461 300 299 46 0.60 483 Example 2 250 275 43 0.91 454 300 283 450.88 460 Example 3 250 277 42 0.62 453 300 285 44 0.59 459 Example 4 250274 39 0.63 451 300 283 46 0.58 458 Example 5 250 282 46 1.02 451 300298 48 0.97 471 Example 6 250 284 20 1.10 450 300 297 25 1.05 472Example 7 250 285 24 1.03 454 300 296 26 0.99 473 Example 8 250 284 230.98 452 300 298 22 0.89 477 Example 9 250 286 18 0.89 453 300 297 230.88 477 Example 10 250 286 23 0.81 460 300 298 23 0.77 485 Example 11250 284 43 0.78 460 300 297 46 0.75 484 Example 12 250 283 20 1.01 457300 296 23 0.98 473 Example 13 250 286 24 0.84 456 300 295 26 0.78 480Example 14 250 284 25 1.05 458 300 298 25 1.03 475

As can be seen from Table 2, the photosensitive resin composition of thepresent invention has high sensitivity, and the composition can give apattern with high resolution. As can be seen from Table 3, as to theelongation and water absorption, the physical properties of the filmobtained by curing at 250° C. were comparable with those of the filmobtained by curing at 300° C. As to the 5% weight reduction temperature,the films obtained by curing at 250° C. gave slightly lower results,although all of the films gave results of 450° C. or higher, whichcauses no practical problems. As to the film produced in Example 10, theamount of outgas when held at 300° C. for 1 hour was examined. As aresult, the amount of outgas from the film cured at 250° C. was 1.3%,which is comparable with 0.95% from the film cured at 300° C.

Examples 15 to 22

Variations of curing method were studied as to the positivephotosensitive resin composition solutions containing the materials usedin Examples 1, 2, 3, 7, 8, 9, 10, and 11 shown in Table 1. Each of thepositive photosensitive resin composition solutions was first appliedonto a silicon wafer by spin coating, and heated at 120° C. for 3minutes, to form a coating film having a thickness of 15 μm. The filmwas then cured by means of Microcure 2100, manufactured by LambdaTechnologies Inc., at a microwave power of 450 W and a microwavefrequency of 5.9 to 7.0 GHz while maintaining the substrate temperatureat 200° C. for 2 hours, to obtain a cured film having a thickness ofabout 10 μm.

Subsequently, the cured film was peeled off using an aqueous solution ofhydrofluoric acid, and washed with water and dried. Physical propertiesof the film, i.e., glass transition temperature (Tg), elongation, and 5%weight reduction temperature were measured. The results are shown inTable 4 below. TABLE 4 5% Weight Photosensitive reduction resin TgElongation temperature composition (° C.) (%) (° C.) Example 15 Materialin 283 40 457 Example 1 Example 16 Material in 274 44 450 Example 11Example 17 Material in 275 44 451 Example 11 Example 18 Material in 28025 454 Example 11 Example 19 Material in 282 26 449 Example 11 Example20 Material in 279 20 448 Example 11 Example 21 Material in 283 21 455Example 11 Example 22 Material in 282 45 457 Example 11

From the results of Examples 15 to 22, it was confirmed that thepolyamide contained in the photosensitive resin composition of thepresent invention effectively undergoes ring-closing dehydration and iscured by irradiation with a pulse of microwave while changing afrequency and while maintaining the substrate temperature at 200° C. Inaddition, from the Table 4 above, it was confirmed that the cured filmobtained by this method has a glass transition temperature, anelongation, and a 5% weight reduction temperature, which are comparablewith the corresponding physical properties of the film formed in thering-closing dehydration at 250° C. using a heating curing oven. Thesefindings confirm that, by irradiation with a pulse of microwave whilechanging a frequency, the photosensitive resin composition of thepresent invention can be cured at a low temperature, compared to thetemperature of curing using a generally used oven filled with nitrogen.

Comparative Examples 1 to 6

In the same manner as in Example 1, 100 parts by weight of thepolybenzoxazole precursor (the component (a)) synthesized in theSynthesis Example was mixed with the component (b) as a sensitizer, thecomponent (c), the compound (d) having a phenolic hydroxyl group, andthe solvent (e) in the predetermined amounts shown in the Table 5 below.10 parts by weight of a 50% methanol solution ofureidopropyltriethoxysilane as an adhesion promoter was further addedthererto. In these Examples, the component (c) was not added, or was anyone of compounds C15-C19 shown below. The resulting solution wassubjected to pressurized filtration using a 3 μm pore Teflon® filter, toobtain a solution of a photosensitive resin composition. TABLE 5Component Compo- Compo- Compo- Compo- (a) nent (b) nent (c) nent (d)nent (e) Comparative Polymer I B1(10) None D2(10) E1(160) Example 1Comparative Polymer I B1(10) C14(2.5) D2(10) E1(160) Example 2Comparative Polymer I B1(10) C15(3) D2(10) E1(160) Example 3 ComparativePolymer I B2(10) C16(3) D1(10) E1(160) Example 4 Comparative Polymer IB2(10) C17(3) D1(10) E1(160) Example 5 Comparative Polymer I B2(10)C18(2) D1(10) E1(160) Example 6In the Table, the figure in each pair of parentheses represents theamount of each component in terms of parts by weight relative to 100parts by weight of the polymer.

Chemical formulae of the components (c) shown in Table 5 are as follows:

Each of the solutions obtained by the aforementioned procedure wasapplied onto a silicon wafer by spin coating, and heated at 120° C. for3 minutes, to form a coating film having a thickness of 11 to 13 μm. Thefilm was then subjected to reduction projection exposure with i-line(365 nm) through a mask using an i-line stepper (FPA-3000iW;manufactured by CANON INC.). After the exposure, the resulting film wasdeveloped using a 2.38% aqueous solution of tetramethylammoniumhydroxide so that the thickness of the residual film became about 70 to90% of the initial thickness. The pattern was then rinsed with water,and examined for measuring minimum exposure energy required for formingthe pattern and resolution. The results are shown in Table 6 below.TABLE 6 Sensitivity Residual film Resolution (mJ/cm²) ratio (%) (μm)Comparative 200 79 2 Example 1 Comparative 250 80 2 Example 2Comparative 210 77 2 Example 3 Comparative 280 73 3 Example 4Comparative 290 72 3 Example 5 Comparative 290 72 3 Example 6

Further each of the solutions obtained by the aforementioned procedurewas applied onto a silicon wafer by spin coating, and heated at 120° C.for 3 minutes, to form a coating film having a thickness of 15 μm. Thefilm was then heated in a nitrogen atmosphere in an inert gas oven at150° C. for 30 minutes, and then further heated at 300° C. for 1 houror, alternatively, at 250° C. for 1 hour to obtain a cured film.Subsequently, the cured film was peeled off using an aqueous solution ofhydrofluoric acid, and washed with water and dried. Physical propertiesof the film, i.e., glass transition temperature (Tg), water absorption,elongation, and 5% weight reduction temperature were measured. Theresults are shown in Table 7 below. TABLE 7 5% Weight Curing Waterreduction temperature Tg Elongation absorption temperature (° C.) (° C.)(%) (%) (%) Comparative 250 277 40 1.56 439 Example 1 300 299 42 1.10480 Comparative 250 275 18 1.66 435 Example 2 300 298 20 1.24 475Comparative 250 278 39 1.57 440 Example 3 300 299 42 1.12 479Comparative 250 276 17 1.58 436 Example 4 300 298 19 1.34 478Comparative 250 275 20 1.56 437 Example 5 300 299 22 1.14 479Comparative 250 273 16 1.87 435 Example 6 300 293 18 1.55 475

As exhibited by the physical properties of films shown in Table 7, it isconsidered that the cyclodehydration reaction does not proceedcompletely in curing at 250° C. in the Comparative Examples, and thewater absorption of the films obtained by curing at 250° C. was high,i.e., about 1.5%, as compared to the water absorption of the filmsobtained by curing at 300° C. The 5% weight reduction temperature of thefilms obtained by curing at 250° C. was lower than 450° C.

Examples 23 to 26 Synthesis Example 3 Synthesis of HydroxylGroup-Containing Diamine Compound (VII)

18.3 g (0.05 mol) of bis(3-amino-4-hydroxyphenyl)hexafluoropropane wasdissolved in 100 ml of acetone and 17.4 g (0.3 mol) of propylene oxideunder a dried nitrogen gas stream and cooled to −15° C. To the resultingsolution was added dropwise a solution prepared ivy dissolving 20.4 g(0.11 mol) of 4-nitrobenzoyl chloride in 100 ml of acetone. Aftercompletion of the addition, the reaction was effected at −15° C. for 4hours, and then the reaction mixture was left stand to room temperature.The white solid precipitate was collected by filtration and dried in avacuum at 50° C. 30 g of the solid thus obtained was then placed in a300-ml stainless steel autoclave, and dispersed in 250 ml of methylcellosolve 2 g of 5% palladium-carbon was added thereto. Hydrogen wasfed to the autoclave to effect a reduction reaction at room temperature.After the reaction was continued for about 2 hours, the palladiumcompound as a catalyst was removed by filtration, and the filtrate wasconcentrated by means of a rotary evaporator to obtain diamine compound(VII). The solid thus obtained was used as it is in the subsequentreaction.

Synthesis Example 4 Synthesis of Hydroxyl Group-Containing AcidAnhydride (VIII)

18.3 g (0.05 mol) of bis(3-amino-4-hydroxyphenyl)hexafluoropropane and34.2 g (0.3 mol) of allyl glycidyl ether were dissolved in 100 g ofγ-butyrolactone under a dried nitrogen gas stream and cooled to −15° C.To the resulting solution was added dropwise 22.1 g (0.11 mol) oftrimellitic anhydride chloride dissolved in γ-butyrolactone whilecontrolling the temperature or the reaction mixture below 0° C. Aftercompletion of the addition, reaction was effected at 0° C. for 4 hours.The resulting solution was concentrated by means of a rotary evaporator,and poured into 1 L of toluene, to obtain acid anhydride (VIII).

Synthesis Example 5 Synthesis of Poly(Imide-Benzoxazole) Precursor

15.1 g (0.025 mol) of hydroxyl group-containing diamine (VII) obtainedin Synthesis Example 3 was dissolved in 50 g of N-methyl-2-pyrrolidoneunder a dried nitrogen gas stream. To the resulting solution were added17.5 g (0.025 mol) of hydroxyl group-containing acid anhydride (VIII)obtained in Synthesis Example 4 and 30 g of pyridine, and reaction waseffected at 60° C. for 6 hours. After completion of the reaction, theresulting solution was poured into 2 L of water, and the solid polymerprecipitate was collected by filtration, and then washed with water,followed by vacuum drying, to obtain a poly(imide-benzoxazole) precursor(hereinafter referred to as “polymer III”).

Synthesis Example 6 Synthesis of Poly(Imide-Benzoxazole) Precursor

Synthesis was conducted under the same conditions as in SynthesisExample 5, except that hydroxyl group-containing diamine (VII) wasreplaced with 5.01 g (0.025 mol) of 4,4′-diaminophenyl ether, to obtaina poly(imide-benzoxazole) precursor (hereinafter referred to as “polymerIV”).

Operations were conducted in the same procedure as in Examples 1 to 14except that, as shown in Table 8, polymer III or IV was used as thecomponent (a) and N-methyl-2-pyrrolidone (hereinafter abbreviated as“E3”) was used as the component (e) and the components (a) to (e) wereblended in the amounts shown in Table 8, and the sensitivity propertiesof the resultant were evaluated. The results are shown in Tables 9 and10 below. TABLE 8 Component Compo- Compo- Compo- Compo- (a) nent (b)nent (c) nent (d) nent (e) Example 23 Polymer III B1(15)  C1(3) D1(12)E3(160) Example 24 Polymer III B3(13) C10(2.5) D2(10) E3(160) Example 25Polymer IV B1(20)  C1(3) D1(13) E3(160) Example 26 Polymer IV B3(15)C11(2.5) D2(10) E3(160)

In the Table, the figure in each pair of parentheses represents anamount of each component in terms of parts by weight relative to 100parts by weight of the polymer. TABLE 9 Sensitivity Residual filmResolution (mJ/cm²) ratio (%) (μm) Example 23 370 78 5 Example 24 350 785 Example 25 520 75 4 Example 26 480 74 5

TABLE 10 5% Weight Curing Water reduction temperature Tg Elongationabsorption temperature (° C.) (° C.) (%) (%) (%) Example 23 250 273 141.15 452 300 305 15 1.09 465 Example 24 250 278 13 1.19 451 300 300 161.08 460 Example 25 250 277 16 1.21 447 300 299 17 1.14 453 Example 26250 280 15 1.20 448 300 302 17 1.15 455

As can be seen from Table 9, the photosensitive resin composition of thepresent invention has relatively high sensitivity, and the compositioncan give a pattern with high resolution. As can be seen from Table 10,as to the elongation and water absorption, the physical properties ofthe film obtained by curing at 250° C. were comparable with those of thefilm obtained by curing at 300° C. As to the 5% weight reductiontemperature, the films obtained by curing at 250° C. gave slightly lowerresults, although all of the films gave results of 450° C. or higher,which have no practical problems.

INDUSTRIAL APPLICABILITY

As described above, the positive photosensitive resin composition of thepresent invention has excellent sensitivity, resolution and adhesion.Furthermore, even when it is used in a low-temperature curing process, apattern having excellent heat resistance, low water absorption andconfiguration can be obtained from the composition. Thus, it is suitablyused for fabricating electronic parts, particularly MRAM which isrequired to be produced in a low-temperature process.

1. A positive photosensitive resin composition comprising: (a) alkalineaqueous solution-soluble polyamide having a polyoxazole precursorstructure; (b) an o-quinonediazide compound; and (c) a latent acidgenerator which generates acid upon heating.
 2. The positivephotosensitive resin composition according to claim 1, wherein thecomponent (a) is a polyamide having a repeating unit represented by thefollowing general formula (I):

wherein U represents a tetravalent organic group, and V represents adivalent organic group.
 3. The positive photosensitive resin compositionaccording to claim 1, wherein the component (c) is a salt formed of astrong acid and a base.
 4. The positive photosensitive resin compositionaccording to claim 1, wherein the component (c) has a decompositionstarting temperature of 140 to 250° C.
 5. The positive photosensitiveresin composition according to claim 1, wherein the component (c) is asalt of toluenesulfonic acid.
 6. The positive photosensitive resincomposition according to claim 1, wherein the component (c) is aniodonium salt.
 7. The positive photosensitive resin compositionaccording to claim 1, further comprising (d) a compound having aphenolic hydroxyl group.
 8. The positive photosensitive resincomposition according to claim 7, wherein the component (d) is acompound represented by the following general formula (II):

wherein X represents a single bond or a divalent organic group, each ofR³ to R⁶ independently represents a hydrogen atom or a monovalentorganic group, each of m and n is independently an integer of 1 to 3,and each of p and q is independently an integer of 0 to
 4. 9. Thepositive photosensitive resin composition according to claim 8, whereinthe group represented by X in the general formula (II) is a grouprepresented by the following general formula (III):

wherein each of two A's independently represents a hydrogen atom or analkyl group having 1 to 10 carbon atoms, and optionally has any one ofan oxygen atom and a fluorine atom or both.
 10. The positivephotosensitive resin composition according to claim 1, wherein thecontent of the component (b) and the content of the component (c) are 5to 100 parts by weight and 0.1 to 30 parts by weight, respectively,relative to 100 parts by weight of the component (a).
 11. The positivephotosensitive resin composition according to claim 7, wherein thecontent of the component (b), the content of the component (c), and thecontent of the component (d) are 5 to 100 parts by weight, 0.1 to 30parts by weight, and 1 to 30 parts by weight, respectively, relative to100 parts by weight of the component (a).
 12. A method for forming apattern comprising the steps of: applying the positive photosensitiveresin composition according to claim 1 onto a supporting substrate anddrying the composition to obtain a photosensitive resin film; exposingthe photosensitive resin film to a ray of active light having apredetermined pattern; and developing the exposed photosensitive resinfilm using an alkaline aqueous solution.
 13. The method according toclaim 12, further comprising a step of subjecting the developedphotosensitive resin film to a heating treatment.
 14. The methodaccording to claim 13, wherein the heating treatment is a treatment ofirradiating the film with a pulse of microwave while changing thefrequency thereof.
 15. The method according to claim 13, wherein theheating treatment is conducted at a temperature equal to or lower than280° C.
 16. An electronic part comprising an electronic device having alayer of pattern obtained by the method for forming a pattern accordingto claim 12, wherein the device comprises the layer of pattern providedtherein as any one of an interlayer insulating layer and a surfaceprotecting film layer or both.
 17. The electronic part according toclaim 16 which is MRAM.